The aim of this proposal is to isolate and characteize bone Gla protein (BGP) or osteocalcin and osteonectin from bovine, and subsequently, from human sources. The bovine material will be used to develop procedures and the human specimens will be obtained following surgical procedures. The techniques which will be used to purify these proteins to homogeneity include classical methods (gel filtration, ion-exchange, chromatography, etc.), as well as monoclonal antibodies as specific immunoabsorbants. The latter technique has already been used by these investigators to isolate bone Gla protein and osteonectin. The proposed chemical characterization of purified "bone-specific" proteins includes (1) amino acid composition and NH2-terminal sequence, (2) molecular weight and subunit characterization, (3) a variety of binding and association studies, including metal ion-binding, absorption onto hydroxyapatite and inhibition of hydroxyapatite-seeded crystal growth, protein-collagen and protein-protein interaction, and self-association.